46 BRITISH EOCENE FLORA. 



There is a marked diminution in the group in the Cretaceous. Baieria from the 

 Komeschichten is limited to vestiges, of stunted form, described as Ferns, while Ginkgo 

 appears in a starved species with small leaves and short thick petiole, described as 

 Adiantum formosum, and by fragments from the Ataneschichten, inappropriately named 

 G. primordialis. In the Arctic Tertiaries, Ginkgo is met with sparingly in Greenland 

 only, where it so much resembles G. adiantoides of the Italian Miocenes that Heer almost 

 directly abandoned his specific name primordialis^ and became doubtful even whether 

 both should not be united with the existing species. Coming south there are small and 

 doubtful fragments from the Baltic Miocene, and it is only again met with in the later 

 Miocenes and Pliocenes of Italy and the South of Prance. It is completely unknown in 

 either the Eocene or Oligocene in temperate Europe, with the one exception of Ettings- 

 hausen's Salisburia eocoenica of Sheppey, about which there is some room for doubt. 



Ginkgo (?) eoc^nica, Ett. and Gard. Plate IX, figs. 31 — 34. 



Salisburia eocoenica, E. and G. Proceed. Roy. Soc, vol. xsix, p. 392, 1879. 



London Clay, Sheppey. 



The fruits or seeds are entirely pyritized, irregularly ovate, and variable in form. 

 The largest measure some eleven millimetres in height by about nine millimetres in 

 breadth, but they are occasionally wider than high, and more or less compressed, varying 

 from seven to barely four millimetres in thickness. They are sharply keeled, the keel 

 is sinuous and the seeds consequently not symmetrical. There is a small truncated 

 projection at one extremity, greatly resembling that seen in the existing seed of Ginkgo, 

 but at the other end of the seed there appears a trace apparently of a scar of attach- 

 ment. 



They are perfectly smooth, and are probably interior casts of the shell filled with 

 amorphous pyrites. They are much smaller and more 

 sharply keeled than in Ginkgo, which they otherwise 

 resemble in general form ; but if the slight scar which they 

 present is truly one of attachment, it would point to a 

 leguminous origin. A great variability in the form of the 

 Fig. 19.— Seed of Fia. 20.— Edge seed is also sccu in the existing species. Several of these 



OinJcgo biloha. view of same. , i • ,i -n. i i n n i.- • i.i 



seeds are preserved m the Bowerbank Collection in the 

 British Museum. They are now difficult to obtain, being either very rare or overlooked 

 by collectors at Sheppey. 



The sole existing representative of the genus is the gigantic G. biloba, apparently 

 indigenous to Northern China, for it is only met with in the immediate vicinity of 



